Dear Bah...

please I need help.
I am a woman in my late Twenties(gradually closing up to 30).
my problem started in my mid twenties when i met this guy. he was so caring and showed me lots of love, things moved so fast, and before i knew it we were everywhere together, i was so much in love then.
The problem started when i discovered i was pregnant for him, i told him i was pregnant and he became furious, he stopped calling, stopped talking to me and even ignored my calls. thank God for my mother, she was my pillar then. till i gave birth to a boy(my sweet angel Tunji), he is my all.
though he has down-Syndrome and rarely talks, always playing and he's so sweet.
The problem now is i met this guy, who really wants to marry me, he seems serious because when i told him about my having a son, he accepted to be his step father.
i have never told him the condition my boy is in, and i'm scared of his reaction if i am to tell him, i love him so much and do not want to loose him.